Field
Embodiments described generally relate to composite products and methods for making and using same. More particularly, such embodiments relate to lignocellulose composite products that include an at least partially cured powdered binder that, prior to curing, includes a powdered carbohydrate and a powdered nitrogen-containing compound and methods for making and using same.
Description of the Related Art
The production of lignocellulose composite products requires an adhesive or a binder to bond the discrete sheets, veneers, particulates, fibers, or other substrates to one another. Typical lignocellulose composite products include oriented strand boards, waferboards, particleboards, fiberboards, and other composite products. Conventional binders used in the production of these composite products are in a liquid state and generally contain a mixture of a resin and a solvent, such that the resin is contained in an aqueous solution or an organic solution. Usually, additives, such as surfactants or thickeners, must be included in the mixture of the resin and the solvent to provide a desirable viscosity for the final binder mixture. Although conventional binders are used to produce finished composite products having desirable properties, such as strength, these liquid state binders tend to take a relatively long time, e.g., about 15 minutes or longer, to cure and/or dry when pressed and heated to form the composite product.
Further, typical binders used in the production of lignocellulose products include formaldehyde-based resins, such as urea-formaldehyde (UF), melamine-formaldehyde (MF), melamine-urea-formaldehyde (MUF), and phenol-formaldehyde (PF). Such resins can potentially release formaldehyde into the environment during the production thereof, during application to a lignocellulose substrate, during curing of the resin/substrate, as well as, from the finished product. Various techniques have been used to reduce the amount of formaldehyde released from formaldehyde-based resins and products that include formaldehyde-based resins. For example, the addition of formaldehyde scavengers to the formaldehyde-based resin and/or various modifications to the particular synthesis steps used to make the formaldehyde-based resin such as the addition of urea as a reactant late in the resin synthesis have been used in an attempt to reduce formaldehyde emission. These attempts to reduce formaldehyde emission, however, are accompanied with undesirable effects such as longer cure times, reduced resin shelf-life, reduced product strength, reduced tolerance for processing variations, and/or inferior moisture resistance.
There is a need, therefore, for composite products made with binder compositions that cure and/or dry faster than conventional binders, have reduced formaldehyde emission, and/or have acceptable or improved internal bond strength and/or other physical properties, and methods for making and using same.